A study designed to determine the single-agent response rate of CPT-11 in a multi-center U.S. trial. The purpose is to assess the anti-tumor activity of irinotecan in patients with newly-diagnosed inoperable non-small-cell lung cancer, to evaluate the qualitative and quantitative toxicities of irinotecan in the patient population, and to characterize the pharmacokinetics and pharmacodynamics of irinotecan and its active metabolite in the patient population.